This invention relates generally to fluid infusion systems and, more particularly, to a new and improved novel latching and retaining mechanism for use in such systems which, upon manipulation of a single latch arm, operates to load a pumping segment into the infusion system and to place pumping, flow control and fluid line monitoring structures of the infusion system into engagement with the pumping segment.
The infusion of fluids into a patient is usually accomplished by means of an infusion administration set in conjunction with controlling apparatus that meters the rate of flow of fluid through the set. Peristaltic type pumps, which function by repetitively occluding successively adjacent sections of tubing in a wave-like motion, have proven particularly attractive for use in controlling fluid flow. They operate externally on the fluid conduits to pump the fluids to the patient and therefore, do not introduce contamination into the system. Additionally, they provide increased precision of control over the fluid flow through the system.
Typically in such systems, a pressure plate provides a rigid surface against which the fluid conduit is pressed while the peristaltic fingers progressively occlude the conduit. The rigid surface is located in a predetermined position for consistency in the pumping operation and may be either spring loaded or fixed in relation to the front of the pump. Should the surface move from the expected position or move outside the expected range of movement, the quantity of fluid pumped may be altered from that desired. It is thus important to provide an accurate mounting structure for holding the pressure plate in a known position.
Due to the environment in which infusion systems may be used, it is often desirable to control or at least limit the pressure within the fluid delivery conduit providing fluid to the patient. When the pressure in the conduit exceeds a predetermined limit, some pumping systems will stop the operation of the pump. Accordingly, some infusion systems incorporate a pressure sensor for monitoring the fluid pressure in the fluid delivery conduit. These pressure sensors rely on correct positioning in relation to the conduit to be sensed, to insure accuracy. Thus, it is desirable to provide a mounting system so that the pressure sensor correctly interfaces with the fluid conduit.
Likewise, it is often important to detect the presence of air in a fluid flow line. Some infusion systems employ structures and associated control systems to monitor a part of the administration set conduit for the presence and quantity of air. Proper positioning of the conduit in the sensor is essential for accuracy in the air-in-line measurement process. Positioning the conduit in the sensor prior to the beginning of the pumping operation is important and providing a mechanism that assists the pump operator in doing so is desirable.
In the case where a fluid conduit segment has a manual flow control device for manual flow control of fluid flow through the conduit (such as for priming) and has a device for peristaltic pump flow control, some interaction with these mechanisms and the peristaltic pump system must occur. For example, free flow through the conduit from the reservoir to the patient is avoided with peristaltic pumps in that at least one peristaltic finger is always occluding the conduit at all times. However, before the conduit is mounted to the peristaltic pump system, a manual flow control device, usually termed a "flow stop" is used to prevent free flow. If the manual flow stop is made a part of the conduit pumping segment, it is desirable to have the peristaltic fingers occlude the conduit before the manual flow stop is moved to the flow position, so that free flow does not occur inadvertently.
In the case where a pumping segment is provided that includes a flow control valve, such as a slide mechanism for manual control over the fluid flow, a pumping section which peristaltic fingers massage to move fluid, a pressure sensing section for engagement with a pressure sensor, and a tubing section that mounts in an air-in-line sensor, ease and reliability in correctly mounting the pumping segment is desirable. Additionally, configuring the pumping segment and interfacing mechanisms of the pumping mechanism so that the pumping segment is properly mounted before the flow control is positioned to permit flow, and so that the pressure sensor and air-in-line sensor engage the appropriate sections of the pumping segment before pumping can begin is desirable.
Hence, those skilled in the art have long recognized the need for an improved interlock, latching and retaining mechanism that receives a pumping segment, retains that segment in the correct position, and locks the segment in a predetermined position so that correct pumping action can occur. There is also a recognized need for a mechanism that times the engagement of the peristaltic mechanism with the pumping segment and the release of the manual flow stop so that an undesired free flow condition is avoided. Also recognized is a need to assist in correctly locating a portion of the pumping segment in an air-in-line sensor before operation of the pumping mechanism. The present invention fulfills all of these needs.